The present invention relates generally to ear phones, also known as “earbuds,” for handheld electronic devices, such as portable media players (“PMP's”) as well as hearing aids, cellular telephones, and other devices adapted for hearing. More particularly, the invention relates to an ear phone adapter that provides enhanced sound isolation, improves retention of the ear phone inside the ear even under extreme activity and perspiration and minimizes acoustical impedance within the ear canal area.
PMP's are popular to use for listening to music while walking or running outdoors or inside on a treadmill, for example. They are commonly used with earbuds, which are miniature speakers that fit into the ears at the entry of the ear canal. Earbuds are comfortable and well suited for this use since they are pocket sized, lightweight and independent pieces that are not as cumbersome to wear or carry as headphones, which have a connecting framework. However, there are a number of drawbacks associated with earbuds. First, they are often ineffective at blocking out ambient noise and preventing leakage of the amplified sound into the surrounding area. Second, the position of the earbud in the ear is often not well controlled or aimed. The result is an erratically shaped passageway for the sound wave to travel as it leaves the speaker inside the earbud and makes its way into the ear canal. Abrupt changes in the direction or area of the passageway through which a sound pressure wave travels will alter both the pressure levels and the molecule motion within the pressure wave and distort the sound produced from the speaker. This type of interference of a sound pressure wave is often called “acoustical impedance” and is well known in the design of horns and wind instruments. Like electrical impedance often specified for speakers, acoustic impedance must be minimized for improved sound quality. The phenomenon of acoustical impedance is readily experienced by simply experimenting with different positions of the earbud within the ear. Third, many users find it difficult to keep the earbud retained in the ear. The cord extending from the earbud is easily snagged, and generally swings or bounces with activity. This movement, combined with perspiration in the ear, can often dislodge the earbud from the ear. In some cases, the earbud can become further entangled in exercise equipment or become an annoying distraction when the listener must repeatedly stop his or her activity to re-secure the earbud. Lastly, fitting the earbud to the ear needs to be accomplished without discomfort to the user. Some users feel discomfort due to the earbuds rigid circular shape which can create too much interference and pressure on the ear.
A number of attempts have been made to design earbuds and related accessories that address the basic problems of retention, the improvement of sound isolation and in ear comfort, but these designs are still significantly lacking in performance in one area or another. One attempt is a thin foam rubber cover that surrounds the ear phone speaker area. The cover adds some grip to the area just outside the ear canal. However, this thin foam easily tears, does not provide improved sound isolation, and the increased grip is generally inadequate to retain the ear piece to the ear with increased levels of activity and motion.
Another attempt to improve retention is an ear piece design with a hook feature that encircles the back side of the ear. First, the hook feature adds considerable bulk to the earbud and is less convenient to carry. Also, the external shape and size of the of the ear in relation to the position, size and angle of entry of the ear canal vary greatly from individual to individual. As a result of the misalignment between speaker and ear canal, sound isolation is difficult to achieve and distortion caused by acoustic impedance becomes problematic.
Yet another attempt to improve retention is to provide earbuds with an “in-ear” elastomeric (often rubber) “insert” portion that fits inside at least a portion of the ear canal. This has the added advantage of improving sound isolation (as explained in more detail below). One existing insert shape that fits inside the ear canal includes a tapered cylinder with a smooth rubber outer surface that is attached to the ear piece by sliding the insert over a rigid tubular support that is formed with the ear phone and extends outwardly from the speaker face. The tubular support allows the passage of sound from the speaker through its center, and its outer surface provides a support and attachment portion for the insert. In some cases, the in-ear insert portions are replaceable with small, medium and large sizes as options. Another insert design includes a spherically shaped hollow outer surface attached to the earbud with a hole through the center for the passage of sound. The spherically shaped design includes a mounting portion that fits onto the earbud over the speaker face.
All of the aforementioned in-ear methods still have drawbacks that cause inadequate retention of the ear piece to the ear canal. This is partly due to the fact that the ear canal has an irregular, non-circular cross section and that the axis or “path” of the ear canal is not linear but rather a circuitous path on its way to the ear drum. The cylindrical elastomeric insert designs described do not conform well to the path of the ear canal due to the rigid structure on which they are mounted. These elastomeric inserts conform less to the shape of the path of the ear canal but rather reshape the ear canal's path to become more the shape of the adapter. The result is a less than optimum fit within the ear canal area, uneven pressure exerted on the ear, and potential discomfort. In addition, because the contours of these elastomeric inserts do not match with the path of the ear canal, gaps can exist and the resiliency of the ear canal to return to its normal shape can act to push out and dislodge the earbud, especially with the help of perspiration and motion from exercise activity.
Another drawback of existing in-ear designs is the smooth surface of the elastomeric profile. When perspiration is introduced, the sweat can migrate into the ear canal and reduce friction by effectively becoming a layer of lubricant between the insert and the ear canal. A hydroplaning effect occurs with heavy perspiration, such that the slightest activity and movement can cause the insert and the ear phone to become quickly dislodged.
Another drawback of existing in-ear designs is that the tubular support used for mounting the insert is poorly shaped to minimize acoustical impedance in that the sound pressure wave travels down a passageway that takes an abrupt change in area from the speaker diameter to the tube diameter and then another abrupt change from the tube diameter as it exists into the ear canal.
In addition to retaining the ear phone in the ear, it is also highly desirable to block out noise from the surrounding environment or from the wind for better audio clarity. This is commonly called “sound isolation” and involves significantly reducing or eliminating air gaps that allow the ingress of outside noise into the ear. Sound isolation also helps reduce the stray audio from the ear buds that may be heard by others, and less volume is needed to hear the audio since it is not competing with outside noise. Using less volume has a direct impact on conserving electrical energy which in turn may extend the duration the battery remains sufficiently charged for use. Another benefit of sound isolation is to help prevent feedback between the earphone speaker and a microphone in the case of a hearing aid or cellular phone.
Unfortunately, due to the drawbacks noted above, existing ear phone products do not provide a comfortable product that is sufficiently retained in place on the ear during physical activities with a desired level of sound isolation.